Go for
Blackest Night
Superman/Batman trades (most are really good)
JSA & Justice Society trades
JLA: Tornadoes Path & Lightning Saga
Power Girl by Amanda Conner
Wonder Woman: The Hiketeia
Wonder Woman by George Perez
Power of SHAZAM
All Star Superman
Batman/Superman/Wonder Woman: Trinity
JLA: Heaven's Ladder
Justice League: A New Beginning
J.L. The Nail & Another Nail
JLA/JSA : Virtue and Vice
The Flash ( any Mark Waid trades)
Legion of Super-Heroes: The Great Darkness Saga
Wrath of the Spectre by Michael Fleisher and Jim Aparo
Green Lantern/Green Arrow by O'Neil & Adams
Superman/SHAZAM: First Thunder
That should keep you busy.
The JSA stuff is really worth it in particular since DC has decided to defecate all over the legacy of the JSA.

Well, that's a really interesting list. Thanks for that.

__________________- Borg? That sounds Swedish. - They don't look Swedish to me!
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- If you don't eat your meat you can't have any pudding! How can you have any pudding if you don't eat your meat!?